I think the breaking ground was that Facebook's primary feature was security. MySpace had it, but they didn't emphasize it, and even when security was on, they

I think the breaking ground was that Facebook's primary feature was security. MySpace had it, but they didn't emphasize it, and even when security was on, they tried to make profiles display like public pages - they just made them sparser. Facebook introduced the completely blank page that you get when you try to go to a restricted profile. It was pretty cutting edge when I registered in 2005-06.